Vitamin D and COVID-19
As we are now just coming out of the lockdown and have been banished to our homes. What might this lack of sunlight affect?
An article in The Lancet looked at whether being deficient in vitamin D resulted in a poorer outcome if contracting COVID-19.
Having been advised to stay at home as much as possible, government health agencies have recommended that people take vitamin D through the summer and autumn during this pandemic. This is particularly important for older people as they are at higher risk of poor outcome from COVID-19 and also vitamin D deficiency.
Interestingly, mortality from COVID-19 has been clearly higher in some countries than others. Many factors could have had a role in this disparity, including differences in the number of elderly population in the country, general health, accessibility and quality of healthcare, and socioeconomic status. However, it is postulated that an overlooked factor could be the relative vitamin D status of the population.
Vitamin D clearly has a well-defined role in calcium and phosphate balance and this in turn affects bone growth and turnover. Low vitamin D has been associated with other non-communicable diseases and with an increased susceptibility to infectious diseases – particularly upper respiratory tract infections.
However, which came first, low vitamin D as a cause or consequence of disease?
Intervention trials have rarely shown any benefit of vitamin D supplementation as a treatment or preventative measure. However, an important exception is in upper respiratory tract infections; a 2017 meta-analysis of individual patient data from 11,321 participants in 25 randomised controlled trials showed that vitamin D supplementation protected against acute respiratory tract infections and patients with very low serum vitamin D concentration gained the most benefit.
A large body of circumstantial evidence now specifically links the outcomes of COVID-19 and vitamin D status.
This wretched virus SARS-CoV-2 emerged and started its spread within the northern hemisphere at the end of 2019 when levels of vitamin D are at their lowest. Nations in the northern hemisphere have borne much of the burden of cases and mortality.
A cross-sectional analysis across Europe showed that COVID-19 mortality was significantly associated with vitamin D status. The only exception to this was the low mortality rates in Nordic countries. It is noted that populations in these countries have a relative vitamin D sufficiency owing to widespread fortification of their foods.
Italy and Spain are also exceptions. The prevalence of vitamin D deficiency in these populations is surprisingly common, possibly as a result of their clothing and catholic religion, whereby women are fully clothed in black.
Black and minority ethnic races also have lower vitamin D because they have darker skin. They seem to be worse affected than Caucasian people by COVID-19. Data from the United Kingdom Office for National Statistics showed that black people in England and Wales are four times more likely to die from COVID-19 than Caucasian people.
Why?
What is the vitamin D effect?
This could be twofold:
- Vitamin D supports the production of antimicrobial peptides in the respiratory epithelium, therefore making infection with the virus and development of COVID-19 symptoms less likely.
- Vitamin D might help to reduce the inflammatory response to infection with SARS-CoV-2. Vitamin D is known to interact with a protein in the renin angiotensin’s pathway the angiotensin-converting enzyme 2 (ACE2), which is exploited by SARS-CoV-2 as an entry receptor. SARS-CoV-2 downregulates expression of ACE2 whilst vitamin D promotes expression of this gene. Vitamin D therefore might help to reduce the inflammatory response to infection with SARS-CoV-2.
Rose Anne Kenny from Trinity College Dublin led the cross-sectional study into mortality and vitamin D status. She is adamant that the whole population should take vitamin D supplements during this pandemic and claims that the circumstantial evidence is very strong.
Adrian Martineau from the Institute of Population Health Sciences at Bart’s, London joined with colleagues from universities around the United Kingdom to launch COVIDENCE UK, a study to investigate how diet and lifestyle factors might influence transmission of SARS-CoV-2.
This study is also investigating the speed of recovery, severity of symptoms and any long-term effects.
Martineau is pragmatic. At best, vitamin D deficiency will only be one of the many factors involved in determining outcome of COVID-19, but it is a deficiency that can be corrected safely and cheaply. There is no downside and every good reason to think there might be benefit.
The London General Practice has advocated investigations for vitamin D deficiency for many years and has encouraged supplementation to acceptable levels with weekly strong dose Colecalciferol.
We are undertaking video consultations as well as face to face and home visits wearing full PPE. We are happy to arrange phlebotomy and measure your vitamin D levels so that we can prescribe the most appropriate dose for you. Please do not hesitate to contact us if you would like to take advantage of any of these services.
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